The CNS myelin associated proteins inhibit neurite outgrowth in nerve cells and neuroblastoma cells, and can also inhibit fibroblast spreading. Such inhibitory proteins include a 35,000 dalton and a 250,000 dalton molecular weight protein and analogs, derivatives, and fragments thereof. The CNS myelin associated inhibitory proteins may be used in the treatment of malignant tumors. The present invention is also directed to antibodies to the CNS myelin associated proteins; such antibodies can be used in the diagnosis and therapies of nerve damage resulting from trauma, infarction, and degenerative disorders of the central nervous system. In a specific embodiment of the invention, monoclonal antibody IN-1 may be used to promote regeneration of nerve fibers over long distances in spinal cord lesions.